Field of the Invention
The present invention relates to a tire vulcanization mold and method for manufacturing tire, more particularly to a tire vulcanization mold with improved high durability blades for molding sipes to a tread portion of a tire to be molded.
Description of the Related Art
Typically, a winter tire designed for use on ice and snow has a tread portion provided with a plurality of thin sipes in order to improve friction force against icy or snowy road by increasing biting edges of sipes. Each sipes of the tread portion is formed using a thin metallic blade of a tire vulcanization mold during tire vulcanized process.
In order to further increase the friction force of the tire tread surface on icy road, it may be important to increase a ground contact area of the tread surface. From this point of view, each blade preferably has a thickness as thin as possible.
Since a thin blade for molding sipe, however, has low bending rigidity, the blade is subject to damage such as a bend, or falling out from the tire vulcanization mold when removing the tire from the mold after the tire vulcanization process. In addition, the tire vulcanization mold typically comprises a plurality of segments that can individually move radially outwardly of the tire for releasing the tire from the mold. Thus, the blade arranged in a circumferentially end region of each segment is subject to a large bending moment from the tread rubber of the tire, when the segment moves radially outwardly of the tire, thereby the blade above is liable to damage.